Definition of Secondary ion mass spectrometry

Secondary ion mass spectrometry (SIMS) is a technique for the characterization of solid surfaces and thin films. It uses the process of ion formation by bombarding the surface to be tested with a highly collimated beam of primary ions. The surface then emits material through a sputtering process - only a fraction of these emitted particles is ionized. These secondary ions are measured with a mass spectrometer to determine the quantitative elemental, isotopic or molecular composition of the surface. SIMS is the most sensitive surface analysis technique, but it is more difficult to obtain quantitative results compared to other techniques.